Python Basics

[Pages:29]Python Basics

June 20th 2018 Xiangyu Qu

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Use package manager (pip)

Show version and root of pip List all installed packages

Show information about a specific installed package Search for a specific package in PyPI repository Install packages Uninstall packages Upgrade a package Install a specific version of a package

Check dependencies Most important one

pip --version or pip3 --version pip3 list

pip3 show [package-name] (e.g. pip3 show numpy) pip3 search [package-name]

pip3 install [package-name 1] [package-name 2] pip3 uninstall [package-name 1] [package-name 2]

pip3 install --upgrade [package-name] pip3 install [package-name]==version

(e.g. pip3 install numpy==1.14.3) pip3 check pip3 --help

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Python virtual environment

Create a virtual environment in python3.4 and above: python3 ?m venv [some optional arguments] path/to/environment/directory in python3.3 and python2: virtualenv [some optional arguments] path/to/environment/directory

example: python3 ?m venv --system-site-packages ./workshop

Activate a virtual environment bash: cmd.exe:

source /bin/activate \Scripts\activate.bat

Exit a virtual environment

deactivate

Get help

python3 ?m venv -h

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Numpy

? Numpy is a scientific computation library for Python ? It is very similar to MATLAB. For a side-by-side comparison, visit

wiki/pages/NumPy_for_Matlab_Users ? The basic unit for computation in Numpy is ndarray, which is similar to array in MATLAB. Numpy ndarray

is 0 indexed, MATLAB array is 1 indexed

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Numpy

? Create array from a list of numbers and element access Numpy

MATLAB

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Numpy

? Create array from built-in functions Numpy

MATLAB

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Numpy

? Array indexing: slicing;

syntax: b = a[i:j] ::== return all elements between i and j-1

Numpy

MATLAB

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Numpy

? Array indexing: get a slice with another integer array or Boolean array

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